The residue (sludge) produced in the decantation ponds of Water Treatment Plants (WTP) has variable composition according to the regional WTP localization, the month of collection and the chemical used to flocculation. In this work the sludge was submitted to physical, chemical and mineralogical characterization. Also, technological trials were realized on ceramic probes to evaluate the possibility of sludge incorporation in ceramic mass used to produce bricks. Linear shrinkage, water absorption, mechanical resistance to flexion, apparent porosity and density were evaluated in samples with different sludge concentration. Also, the effect of the chemical product used by the WTP to flocculate the solid particles on the probe ceramic properties was evaluated. The mineralogical analysis showed that the sludge and the ceramic mass had equivalent composition. As a general rule the sludge incorporation make worse the ceramic properties of the probes. Depending on the temperature of firing and the sludge concentration, the measured values can be in accordance with the limit-accepted values to produce bricks. The sludge flocculated by chemicals with aluminum is more deleterious than that obtained by using chemicals with iron. The results indicated that ETA sludge can be mixed to the raw material to produce massive bricks.
sludge; structural ceramic; waterworks; brick
